A conventional motor housing is shown in FIG. 1 . The housing 10 is integrally shaped type and has an outer body 11 with unenclosed upper and lower parts. In the development stage, the outer body 11 to be used is generally made from steel or aluminium material, and a stator core (not shown in FIG. 1) is fit tightly in it. For the outer body 11 is shaped, it is necessary to heat up the outer body 11 to expand the fitting space extent for the stator core inserted in it by means of a special fixture, and the stator core is fit tightly with the outer body when the outer body 11 is cooled down. However, in the development stage, it is possible that the stator core may not meet the desired characteristics and sometimes, it is necessary to remove and change it. But, the cooled outer body 11 is fit tightly with the stator core, so it is difficult to separate them from each other, therefore, the outer body 11 is generally to be destroyed for separating the stator core from it. That causes large consumption of the outer body 11, meanwhile, when the outer body 11 is fit with the stator core, a heating device must be provided to expand the fitting space extent of the outer body for the stator core inserting and the tight fit can not be obtained until the heated element is cooled down, which results in a complex assembling process and time expending. In case of removing and changing the stator core, the outer body 11 must be destroyed so that the stator core can be removed by a special fixture, however, the stator core may be damaged carelessly in the destroying process of the outer body 11, resulting in development cost increasing. Therefore, the inventor develops a motor housing which features its simple assembly and cutting down working hours and cost for a motor development.